Machine for burnishing an elongated workpiece



June 9, 1964 B. KUNZE MACHINE FOR BURNISHING AN ELONGATED WORKPIECE 3 Sheets-Sheet 1 Filed Feb. 14, 1962 FIG.2

INVENTOR. BERNHARD KUNZE ATTORNEf FIG.3

June 9, 1964 B. KUNZE MACHINE FOR BURNISHING AN ELONGATED WORKPIECE 3 Sheets-Sheet 2 Filed Feb. 14, 1962 INVENTOR. BERNHARD KUNZE FIG.5

ATTORNEY j June 9, 1964 B. KUNZE 3,136,029

MACHINE FOR BURNISHING AN ELONGATED WORKPIECE Filed Feb. 14, 1962 3 Sheets-Sheet 5 FIG.8

FIG. 9 INVENTOR.

BERNHARD KUNZE BY M 40 ATTORNEY f United States Patent 3,136,029 MACHINE FOR 'BURNISHING AN ELONGATED WORKPIECE Bernhard Kunze, Erkelenz, Rhineland, Germany, assignor to Wilhelm Hegenscheidt Komrnanditgesellschaft,

Erkelenz, Rhineland, Germany, a partnership Filed Feb. 14, 1962, Ser. No. 173,224 Claims. (Cl. 29--90) My invention relates to a machine for burnishing an elongated workpiece having a circular cross-section, such as a cylindrical or a slightly tapered rod.

It is the object of my invention to provide an improved machine of this type in which a group of burnishing rollers circumferentially distributed about the workpiece performs the dual function of smoothening the surface of the workpiece by pressure exerted thereon and of feeding the workpiece in its axial direction while keeping it centered in floating condition, the machine being free from any elements, such as centers, which would engage the workpiece during the burnishing operation in addition to the burnishing rollers and, therefore, would be liable to exert undesirable stresses thereon.

Moreover, it is an object of my invention to provide a burnishing machine of the character described in which the positions of the burnishing rollers may be easily and accurately adjusted so as to ensure maximum efficiency with respect to both the smoothening elfect and the feeding effect exerted by the rollers on the workpiece.

With the aforesaid objects in view, my invention consists in the novel combinations and arrangements of parts hereinafter described in their preferred embodiments, pointed out in the subjoined claims and illustrated in the annexed drawings. It is to be understood, however, that my invention is in no way restricted to the details of such embodiments but is capable of numerous modifications within the scope of the subjoined claims and that the terms and phrases used in the description of the preferred embodiments following hereinafter have been chosen for the purpose of explaining rather than that of restricting or limiting my invention.

' In the drawings:

FIG. 1 is a diagrammatic side view illustrating how two of a group of three burnishing rollers engage the workpiece in a machine constructed according to one embodiment of the present invention, the view being, in elfect, a section on the line 11 of FIG. 3 looking in the direction of the arrows,

FIG. 2 is a diagrammatic side View illustrating how the third roller of the group of rollers engages the workpiece shown in FIG. 1,

FIG. 3 is a plan view showing the whole group of the burnishing rollers in engagement with the workpiece,

FIG. 4 illustrates supporting means for rotatably mounting one of the burnishing rollers, the view being partly in section along the plane 44 of FIG. 5, the roller being shown in the zero position of its adjustment,

FIG. 5 is a part plan view, part section, of the roller supporting means shown in FIG. 4, the other two rollers and their supports being also shown fragmentarily.

FIG. 6 is a View similar to that of FIG. 3 showing the area of pressure contact between the workpiece and one of the burnishing rollers,

FIG. 7 is a fragmentary plan view on a reduced scale of one embodiment of machine made according to this invention, and having three roller supports such as shown in FIGS. 4 and 5, the three roller supports being shown in the zero positions of their angular adjustments relative to the workpiece,

FIG. 8 is a vertical section taken through a machine built according to a preferred embodiment of my invention, the section being taken along the plane 8-8 of FIG. 9, and

FIG. 9 is a plan view of the machine shown in FIG. 8.

For the purpose of burnishing an elongated workpiece having a circular cross-section, such as a cylindrical rod or a slightly tapering rod 10, the embodiment of my invention illustrated in FIGS. 1 to 7 is provided with supporting means for rotatably mounting a group of three burnishing rollers 12, 13 and 14 in positions circumferentially distributed about'a straight feed path having an axis 15 coinciding with that of the workpiece 10. At least two of the three rollers, for instance the rollers 12 and 13, are mounted in a position in which a central point of each roller, for instance the center 16 of the top face 17 thereof, is spaced from the axis 15 of the feed path a distance D amounting substantially to the sum of the radii of the roller and of the workpiece 10. The axis 18, 18 or 18", respectively, of each roller is so inclined as to cross the axis 15 of the feed path obliquely at a location which is so far remote from the roller and above the same that it is not shown on the drawing. At this location the axis 18 passes the axis 15 at a distance C, FIG. 3, which is smaller than D. This means that the roller axis 18 intersects at an acute angle a firstplane 20, FIG. 3, which contains the axis 15 and passes through the point 16 and also intersects a second plane 21 which passes through the point 16 and extends at right angles to the first plane 20 and parallel to the axis 15. The axis 18' of roller 13 and the axis 18" of roller 14 are similarly inclined. These axes, when revolving about the axis 15, describe a common hyperboloidal surface coaxially surrounding the axis 15.

Moreover, means are provided for imparting rotation to at least one of the three rollers 12, 13 and 14, the other rollers being freely rotatably mounted. The three rollers 12, 13 and 14 constitute the only elements of the machine which engage the workpiece 10 during the bur-' nishing operation and exert pressure thereon. This pressure has two components indicated in FIG. 2 by the arrows 23 and 24, the component force 23 acting lengthwise on the workpiece 10 to feed it along the axis 15, whereas the component force 24 extends in peripheral direction causing the workpiece to spin about its axis 15.

In FIG. 6 the area of pressure contact between the workpiece 10 and a burnishing roller, such as 12, is illustrated. This area shown at 25 has the shape of a tear drop. This peculiar shape is due to the oblique disposition of the roller axis 18 with respect to the plane 21. If the roller axis would extend parallel to the workpiece, the area of the pressure contact would have a substantially rectangular shape.

Owing to the rotation of the workpiece relative to the three axes 18, 13' and 18" of the burnishing rollers, the surface of the workpiece will be smoothened owing to the high pressure exerted thereon within the area 25. This area will travel on the surface of the workpiece along a helical line, the inclination of the roller axis 18 or 18' or 18" respectively, to the plane 20 being so small that the pitch of the helical line will be a fraction only of the length of the area 25. The smoothening or polishing effect exerted by the burnishing rollers is caused by a slight compression of the surface stratum of the material of the workpiece within the area 25. As a result, the workpiece will be slightly extended in axial direction. Owing to the fact, however, that the machine is free from any elements which would engage the workpiece in addition to the burnishing rollers and, therefore, might interfere with such axial extension, the workpiece will not be subjected to any axial stresses such as occur in prior burnishing machines in which the workpiece is engaged by and held between centers. Hence, the absence of any such centers will ensure that the workpiece will not be bent but will remain perfectly straight when passing through the machine along the axis of the feed path.

It is another advantage of my invention that the axis 15 being held in a floating equilibrium position in which the pressures exerted upon the workpiece by the three burnishing rollers will balance each other is free to move laterally, variations of such equilibrium position being liable to occur owing to flexures of the mountings of the three rollers or owing to differences in the compression of the workpiece material effected by the three rollers. The floating condition of the workpiece contributes to the elimination of any bending stresses in the workpiece which are liable to occur in prior machines inwhich the workpiece is held between centers or between stationary guide-ways.

Hence, it will be appreciated that my novel machine is capable of burnishing the workpiece by superficial compression of the material thereof, while preserving the perfectly straight condition of the workpiece.

While each of the three burnishing rollers may be connected with driving means imparting rotary motion thereto, it will suflice to drive one of the three rollers as through means such as illustrated in FIG. 8, for instance. This will result in a very simple and compact construction requiring neither special feeding means for the workpiece nor any guiding means therefor.

Another advantage of my invention is the elimination of the necessity of providing the end faces of the Workpiece with bores for engagement of centers or the like. The operation of the machine is extremely simple as the workpiece needs only be placed between the burnishing rollers before rotation is imparted thereto. This is of particular advantage where the workpiece is supplied to the machine by automatic conveying means.

A suitable embodiment of the supporting means for rotatably mounting each of the three burnishing rollers 12, 13 and 14 is illustrated in FIGS. 4 and 5. This supporting means comprises a frame 30, a bracket 31 and a bearing member 32. The bracket 31 is formed by a bushing integral with a substantially tangential flange 33 which is adjustably mounted on a plane face 34 of the frame which extends parallel to the axis 15 of the straight feed path for the workpiece. The bracket is pivotally mounted on the frame for adjustment about a first axis 35 which extends at right angles to the axis 15 of the feed path. For this purpose, the flange 33 is provided with a bore and a bolt 35 disposed coaxially with respect to the axis 35 passes through this bore into said frame 30 to which it is suitably fixed, for instance by threaded engagement. Moreover, the flange 33 is provided with arcuate slots 36 whose centers of curvature coincide with axis 35. Headed bolts 37 threadingly engaged in the frame 30 pass through the slots 36 and serve to clamp the bracket 31 to the frame 30 in adjusted position.

The bearing member 32 provided for the burnishing roller 12 has a cylindrical stern rotatably mounted within the bushing 31 and a head 39 having a bore 40 and a recess 41 intersecting said bore 40 transversely. Moreover, the bearing member 31 is a composite member composed of a base part 42 and a cover part 43 having adjoining faces extending parallel to the axis 44 of the bushing 31, the portions of the head 39 integral with the component parts 42 and 43 being spaced to accommodate the disk-shaped burnishing roller 12 between them, whereas a pair of trunnions integral with the roller 12 are journaled within the coaxial bore 40. Preferably, the axis 44 coincides with one of the end faces of the burnishing roller 12 and intersects the axis 35 at right angles. The component part 42 of the bearing member 32 has a projecting coaxial threaded stem 45 projecting therefrom and through a washer 46 and bearing a nut 47. The Washer 46 engages the end face of the bushing 31 and thus permits a shoulder 48 of the bearing member 32 to be tightly drawn against the end face of the bushing 31, when the nut 47 is tightened upon suitable angular adjustment of the bearing member 32 within the bracket 31, 33. The axes of adjustment 35 and 44 intersect each other at right angles.

The smooth cylindrical surface of the burnishing roller 12 is confined by a pair of parallel circles 49 and 50. The axis 35 extends substantially through one of these circles, to wit through the circle 50. The diameter of the cylindrical surface of roller 12 exceeds the axial width of the peripheral surface, such width being determined by the axial distance of the circles 49 and 50.

The supporting means described hereinabove with reference to FIGS. 4 and 5 offers the advantage that the angle formed between the roller axis and the plane 21 shown in FIGS. 1, 2 and 3 determining the shape of the area 25 will be maintained invariably, while the angle between the roller axis and the plane 20 determining the feeding eflect may be changed be rotation of the bearing member 32 about axis 44. Inversely, the shape of the contact pressure area 25 may be changed by angular adjustment of the bracket 33 about axis 35 without affecting the feeding effect established by adjustment of the hearing member about axis 44.

In FIG. 7 the mountings for the three rollers 12, 13 and 14 are shown. These may be identical as stated above; and, as also stated above, one or all of the three rollers may be driven. Obviously, a motor drive such as shown in FIG. 8 may be used for this purpose.

In FIGS. 8 and 9 I have illustrated another embodiment of my invention.

A horizontal table 52 carried by a frame 54 has a rear upright flange 56 in which a forwardly projecting threaded bolt 58 is fixed. A bracket 60 is pivotally mounted on bolt 58 for angular adjustment and provided with arcuate slots 59 concentric with respect to the bolt 58 similar to the slots 36 of FIG. 4. Clamping bolts 62 pass through these slots and threadingly engage threaded bores provided in the flange 56 for the purpose of clamping the bracket 60 thereto in angularly adjusted position.

The bracket 60 is formed with an upright bearing 64 in which a stub shaft 66 is journaled which on its upper end carries a roller 68 fixed thereto whose diameter is larger than that of the bearing 64.

A vertical shaft 70 carrying a pulley 72 fixed to its lower end is suitably journaled in the frame 54 by a bearing not shown and projects upwardly through an aperture provided in the table 52 into the vicinity of the stub shaft 66. A flexible clutch 73 connects the shafts 66 and 70 in a manner permitting the angular adjustment of bracket 60 about bolt 58.

Rotation may be imparted to shaft 70 by an electric motor 74 mounted on the frame 54 and drivingly connected with the pulley 72 by a pulley 76 and belts 78.

The roller 68 is more in the nature of a supporting roller to brace the workpiece against the pressure exerted thereon by the two other rollers 80 and 82. The three rollers are rotatably mounted in positions circumferentially distributed at substantially the same level about a straight vertical feed path for the workpiece W, such feed path extending from a workpiece support 84 upwardly along an axis 96 through an aperture 86 provided in the table 52. The workpiece support 84 is carried by a vertical rod 88 mounted for limited axial movement in bearings 90, 93 fixed to the frame 54 and adapted to be moved from a lower position to an upper position by depression of a pedal 91 which is pivotally mounted on the lower bearing 93 and has a pin acting on the rod 88.

While the first bracket 60 is mounted on the one side of the vertical feed path, a second bracket 92 is mounted on the opposite side of the feed path for adjustment about a substantially horizontal axis 94, FIG. 9, which extends near the axis 96 of the feed path. The bracket 92 is secured in any adjusted position by screws 95 which pass through arcuate slots 97 in the bracket and which thread into the flange 56. The slots 97 are curved about the axis 94. A substantially horizontal cylinder 98 is integral or otherwise fixed to the bracket 92 so as to extend substantially radially with respect to the feed path 96 and a piston 100 movable in the cylinder has a piston rod 102 fixed thereto which extends from both ends of the cylinder, the end extending towards the feed path being provided with a fixed head 104. The two burnishing rollers 80 and 82 are journaled on the head 104 in positions which have been explained herein above with reference to FIGS. 1, 2 and 3. Hence, the axis 106 of each roller 80 or 82 is inclined at acute angles with respect to a first plane 108 containing the axis 96 of the feed path and a central point of the roller and with respect to a second plane 110 which contains the central point of the roller and is normal to the first plane 108.

A third bracket 112 is splined on the piston rod 102 and is adjustably mounted about the axis of the piston rod 102. In the embodiment shown, the bracket 112 is held between the opposed ends of a pair of adjusting screws 114 and 116 threadingly engaged in projections 118 of the cylinder 93 extending to points below and spaced from the piston rod 102. Therefore, the angular position of the piston rod 102 may be changed by suitable adjustment of the screws 114 and 116. A change of such angular position combined with a suitable angular adjustment about axis 94, however, will change the disposition of the axes 106 so as to secured the desired shape of the contact pressure area, such as 25 in FIG. 6, and of the axial feeding component of the pressure.

Suitable hydraulic means are provided for exerting pressure on the piston 100 alternatively in a direction towards the feed path or in a direction away therefrom. In the embodiment shown such hydraulic means are constituted by a source of pressure liquid having a pressure pipe and a return pipe and by a reversing valve connecting said pipes alternatively with one or the other of a pair of ducts 120 leading to the ends of the cylinder 98. The source of pressure and the reversing valve are encased in a housing 122.

The machine operates as follows:

The reversing valve is shifted by a handle (not shown) to a position in which the piston 100 is moved to its righthand position thus withdrawing the burnishing rollers 80 and 82 from the roller 68. The workpiece support 84 is so adjusted that the workpiece to be treated when placed with its lower end on the work-support 84 will terminate at its upper end within a horizontal plane intersecting the three rollers 68, 80 and 82. This adjustment may be easily effected by means of the pedal 91. Then the motor 74 is started and the handle connected with the reversing valve is shifted to its other position causing the rollers to firmly clamp the workpiece between them and to feed it upwardly, while the workpiece is held in freely floating positions. When the lower end of the workpiece disengages the rollers, it will be manually discharged from the machine.

The advantages of the invention as here outlined are best realized when all of its features and instrumentalities are combined in one and the same structure, but useful devices may be produced embodying less than the whole.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the combination.

While the invention has been described in connection with a number of preferred embodiments thereof, it will be understood that it is capable of further modification, and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains, and as fall within the scope of the invention or the limits of the appended claims.

What I claim is:

1. A machine for burnishing an elongated workpiece which has a circular cross-section, said machine comprising a group of three rollers each having a smooth cylindrical surface and a diameter exceeding the axial width of its peripheral surface, supporting means for rotatably mounting said group of rollers in positions circumferentially distributed about a straight feed path for the workpiece, each one ,of at least two of said rollers being supported by said supporting means in a position in which an axial point of said roller is spaced from the axis of said feed path a distance amounting substantially to the sum of the radii of said roller and of said workpiece and in which the axis of said roller crosses the axis of said feed path obliquely at a substantial distance smaller than said sum at a point remote from said roller, and means for imparting rotation to at least one of said rollers, said machine being free from elements which would interfere with axial feed of the workpiece along said path in engagement with said group of rollers only, whereby said rollers smoothen the peripheral surface of the workpiece while exerting an axial feeding force thereon.

2. A machine as claimed in claim 1 in which said supporting means comprises a frame, a bracket pivotally mounted on said frame for adjustment about a first axis extending at right angles to said feed path, a bearing member rotatably mounted on said bracket for rotary adjustment about a second axis extending radially with respect to said feed path, said bearing member being provided with a bearing for at least one of said rollers, the axis of said bearing extending transversely to said first axis and to said second axis.

3. A machine as claimed in claim 2 in which said smooth cylindrical surface is confined by a pair of parallel circles and in which said second axis extends substantially through one of said circles.

4. A machine as claimed in claim 1 comprising a frame, a cylinder mounted thereon with its axis extending radially with respect to said feed path, a piston movable in said cylinder, a piston rod fixed to said piston and extending from said cylinder towards said feed path and provided with a head adjacent thereto, said two of said rollers being mounted on said head with their centers equally spaced from the axis of said piston rod.

5. A machine for burnishing an elongated cylindrical workpiece, said machine comprising a frame, a group of three burnishing rollers each having a smooth cylindrical surface, supporting means for rotatably mounting said group of burnishing rollers in positions circumferentially distributed at substantially the same level about a straight vertical feed path for the workpiece, said supporting means including a first bracket adjustably mounted on said frame on one side of said feed path and formed with a bearing having a vertical axis, a first one of said burnishing rollers being rotatably mounted in said bearing for engaging a workpiece fed along said path, said supporting means further including a second bracket mounted on the opposite side of said feed path for adjustment about a substantially horizontal axis extending near the axis of said feed path, a substantially horizontal cylinder fixed to said second bracket so as to extend substantially radially with respect to said feed path, a piston movable in said cylinder, a piston rod fixed to said piston and extending from said cylinder towards said feed path and provided with a fixed head, two of said rollers being journaled on said head in positions in which the axis of each roller is inclined at an acute angle with respect to a first plane containing the centerline of the feed path and a central point of said roller and with respect to a second plane containing said central point and normal to said first plane, a vertical shaft journaled in said frame below said first one of said rollers, a flexible clutch connecting said shaft to said first roller, driving means mounted on said frame and connected to said shaft, hydraulic means for exerting pressure on said piston in a direction towards said feed path, a 10 References Cited in the file of this patent UNITED STATES PATENTS Hayden Apr. 7, 1874 Hayden Apr. 7, 1874 Schmidt Sept. 1, 1936 

1. A MACHINE FOR BURNISHING AN ELONGATED WORKPIECE WHICH HAS A CIRCULAR CROSS-SECTION, SAID MACHINE COMPRISING A GROUP OF THREE ROLLERS EACH HAVING A SMOOTH CYLINDRICAL SURFACE AND A DIAMETER EXCEEDING THE AXIAL WIDTH OF ITS PERIPHERAL SURFACE, SUPPORTING MEANS FOR ROTATABLY MOUNTING SAID GROUP OF ROLLERS IN POSITIONS CIRCUMFERENTIALLY DISTRIBUTED ABOUT A STRAIGHT FEED PATH FOR THE WORKPIECE, EACH ONE OF AT LEAST TWO OF SAID ROLLERS BEING SUPPORTED BY SAID SUPPORTING MEANS IN A POSITION IN WHICH AN AXIAL POINT OF SAID ROLLER IS SPACED FROM THE AXIS OF SAID FEED PATH A DISTANCE AMOUNTING SUBSTANTIALLY TO THE SUM OF THE RADII OF SAID ROLLER AND OF SAID WORKPIECE AND IN WHICH THE AXIS OF SAID ROLLER CROSSES THE AXIS OF SAID FEED PATH OBLIQUELY AT A SUBSTANTIAL DISTANCE SMALLER THAN SAID SUM AT A POINT REMOTE FROM SAID ROLLER, AND MEANS FOR IMPARTING ROTATION TO AT LEAST ONE OF SAID ROLLERS, SAID MACHINE BEING FREE FROM ELEMENTS WHICH WOULD INTERFERE WITH AXIAL FEED OF THE WORKPIECE ALONG SAID PATH IN ENGAGEMENT WITH SAID GROUP OF ROLLERS ONLY, WHEREBY SAID ROLLERS SMOOTHEN THE PERIPHERAL SURFACE OF THE WORKPIECE WHILE EXERTING AN AXIAL FEEDING FORCE THEREON. 